Reagent for use in the measurement of hydrogen peroxide in sample, method of preparation of same as well as process and apparatus for use thereof in the measurement of hydrogen peroxide

Abstract

 A luminol serving as a luminescent reagent is caused to react with a catalase or an immobilized catalase in order to decompose hydrogen peroxide therein. When the catalase is used, the catalase is removed from the reagent, or the reaction between the catalase and the hydrogen peroxide of the reagent is stopped by adding an inhibitor, such as sodium azide, thereto. When the concentration of the catalase is previously adjusted to be 10 to 200 U/ml, it is not required to remove the catalase from the reagent and to cause the reaction between the catalase and the hydrogen peroxide of the reagent to be stopped. This reagent is mixed with a hydrogen peroxide to be tested and a catalyst, and the quantity of light produced by the reaction between the reagent and the hydrogen peroxide is measured. The content of the hydrogen peroxide is determined on the basis of the quantity of light produced.

Description

BACKGROUND OF THE INVENTION

(Field of The Invention)

[0001] The present invention relates to a reagent for use in the measurement of hydrogen peroxide in a sample, a method for preparing the same and a process for measuring the hydrogen peroxide in the sample by using the reagent. More specifically, the invention relates to a reagent which can be also used for the measurment of a small amount of hydrogen peroxide in a sample.

(Description of The prior Art)

[0002] In clinical examinations, the content of hydrogen peroxide is often measured. When the quantitative analysis of a component, such as a glucose, a cholesterol, an amino acid, a polyamine or the like, in an organism is performed, the component is caused to react with an oxidase to produce hydrogen peroxide, and thereafter the hydrogen peroxide content is determined.

[0003] In the Enzyme Immnoassay (EIA) Method, an antigen or an antibody, such as a hormone, a protein or the like, are labelled with an oxidase, such as glucose oxidase or the like, and thereafter the latter is caused to react with a substrate, which is glucose when the oxidase is glucose oxidase, to produce hydrogen peroxide. The absorbance of the hydrogen peroxide obtained is thereafter measured by using a dye, such as 4-aminoantipyrine so that the content thereof can be determined, and thereby the antigen or the antibody can be analyzed.

[0004] Instead of the dye, chemiluminescent material, such as a luminol, a lucigenin and so forth, which reacts with a hydrogen peroxide to produce a light in the presence of a catalyst, can be used for the determination of the hydrogen peroxiede. These methods are effective for the analysis of chemical components of the organism since the hydrogen peroxide content can be precisely measured.

[0005] In cases where the components of an organism are analyzed by the aforementioned methods, it is very important to acurately determine the content of hydrogen peroxide in a sample.

[0006] When the content of hydrogen peroxide is measured according to aforementioned methods, the luminescent reagent and the catalyst are mixed with various concentrations of hydrogen peroxide, the concentrations of which are previously determined, before the sample is measured. Thereafter, the quantities of emitted light due to the reactions between the luminescent reagent and the hydrogen peroxide in the presence of the catalyst are measured. On the basis of these results, a calibration curve representing the relationship between the hydrogen peroxide and the quantity of emitted light is made. Thereafter, the content of the hydrogen peroxide produced by the reaction between the sample and the oxidase is determined on the basis of the calibration curve.

[0007] However, when the content of the hydrogen peroxide is determined by causing the luminescent material to produce light in the presence of the catalyst according to the aforementioned method, it is difficult to accurately determine the content of the hydrogen peroxide in the sample if the content thereof is low, i.e. less than 10⁻⁶ mol/l. Because a small amount of hydrogen peroxide is included in the luminescent material, so that the proportion of the hydrogen peroxide in water solutions containing the luminescent material and the catalyst to that in the sample is relatively high when the content of the hydrogen peroxide in the sample is low.

[0008] Accordingly, it is a principal object of the present invention to provide an improved reagent for use in the measurement of hydrogen peroxide in a sample.

[0009] It is a particular object of the invention to provide an improved reagent by which low concentrations of hydrogen peroxide in a sample can be more accurately measured than conventional reagent.

[0010] It is another object of the invention to provide a method for the preparation of a reagent used in the measurement of hydrogen peroxide.

[0011] It is another subject of the invention to provide a process for measuring the content of hydrogen peroxide by using a reagent.

[0012] It is a further object of the invention to provide an apparatus for measuring the quantity of light produced by the reaction between a sample and a reagent in the presence of a catalyst.

[0013] Further objects and advantages will appear hereinbelow.

SUMMARY OF THE INVENTION

[0014] In accordance with the present invention the foregoing objects and advantages are readily obtained.

[0015] According to one aspect of the invention, a process for measuring the content of hydrogen peroxide in a sample comprises:
    mixing a reagent including a hydrogen peroxide with a catalase to decompose the hydrogen peroxide of the reagent;
    adding an inhibitor, by which the reaction between the catalase and the hydrogen peroxide is stopped, to the mixture of the catalase and the reagent;
    adding the reagent to the sample; and
    measuring the content of hydrogen peroxide in the sample.

[0016] In this case, the inhibitor is preferably a sodium azide.

[0017] According to another aspect of the invention, a process for measuring the content of hydrogen peroxide in a sample comprises:
    mixing a reagent including a hydrogen peroxide with a catalase, the concentration of which is 10 to 200 U/ml based on the total volume, to decompose the hydrogen peroxide of the reagent;
    adding the reagent to the sample; and
    measuring the content of hydrogen peroxide in the sample.

[0018] According to another aspect of the invention, a process for measuring the content of hydrogen peroxide in a sample comprising:
    bringing a reagent including a hydrogen peroxide into contact with an immobilized catalase to decompose the hydrogen peroxide in the reagent;
    adding the reagent to the sample; and
    measuring the content of hydrogen peroxide in the sample.

[0019] The reagent may be caused to pass through a column, in which the immobilized catalase is packed, to come into contact with the immobilized catalase. The immobilized catalase may comprise a catalase which is immobilized on a carrier formed by a reaction between a water insoluble carrier and a polyfunctional reagent.

[0020] According to another aspect of the invention, a reagent for use in the measurement of a hydrogen peroxide in a sample comprises a luminescent reagent and a catalase, the concentration of which is 10 to 200 U/ml based on the total volume.

[0021] The luminescent reagent is preferably a luminol.

[0022] According to another aspect of the invention, a reagent for use in the measurement of hydrogen peroxide in a sample comprises a luminescent reagent and an immobilized catalase.

[0023] The immobilized catalase may comprise a catalase immobilized on a carrier which is formed by a reaction between a water insoluble carrier and a polyfunctional reagent. The water insolble carrier is preferably an aminopropyl-CPG (controlled pore glass). The polyfunctional reagent is prefarably a glutaraldehyde. The luminescent reagent is preferably luminol.

[0024] According to another aspect of the invention, a method for producing a reagent for used for use in the measurement of a hydrogen peroxide in a sample comprises the steps of:
    providing a luminescent reagent including hydrogen peroxide; and
    adding a catalase to the luminescent reagent to decompose the hydrogen peroxide therein, and thereafter removing said catalase remaining in the luminescent reagent.

[0025] According to another aspect of the invention, a method for producing a reagent for use in the measurement of a hydrogen peroxide in a sample comprises the steps of:
    providing a luminescent reagent including hydrogen peroxide; and
    adding a catalase to the luminescent reagent to decompose the hydrogen peroxide therein, and thereafter causing the reaction between the catalase and the hydrogen peroxide in the luminescent reagent to be stopped.

[0026] Preferably, an inhibitor, by which the reaction between the catalase and the hydrogen peroxide in the luminescent reagent is stopped, is added to the mixture of the catalase and the luminescent reagent. The inhibitor is preferably a sodium azide.

[0027] According to another aspect of the invention, a method for producing a reagent for use in the measurement of hydrogen peroxide in a sample comprises the steps of:
    providing a luminescent reagent including hydrogen peroxide; and
    adding a catalase to the luminescent reagent to decompose the hydrogen peroxide therein, the amount of the catalase being previously adjusted to sufficiently decompose the hydrogen peroxide in the luminescent reagent and not to affect the hydrogen peroxide in the sample when the reagent is added to the sample.

[0028] The concentration of the catalase is preferably 10 to 200 U/ml based on the total volume of the luminescent reagent and the catalase.

[0029] According to another aspect of the invention, a method of hydrogen peroxide in a sample comprises the steps of:
    providing a luminescent reagent including hydrogen peroxide; and
    causing the luminescent reagent to pass through a column, in which an immobilized catalase is packed, to decompose the hydrogen peroxide in the luminescent reagent.

[0030] According to another aspect of the invention, a method for producing a reagent for use in the measurement of hydrogen peroxide in a sample comprises the steps of:
    providing a luminescent reagent including a hydrogen peroxide; and
    adding an immobilized catalase to the luminescent reagent to decompose the hydrogen peroxide in the luminescent reagent.

[0031] The immobilized catalase may comprise a catalase immobilized on a carrier which is formed by a reaction between a water insoluble carrier and a polyfunctional reagent.

[0032] According to another aspect of the invention, an apparatus for detecting light produced by the reaction between a luminescent reagent and hydrogen peroxide in a sample in the presence of a catalyst for measuring the content of the hydrogen peroxide in the sample comprises:
    a first vessel in which the luminescent reagent is stored;
    a second vessel in which the catalyst is stored;
    housing means for defining an optically sealable hollow chamber, in which a cell is placed;
    a column in which an immobilized catalase is packed, the immobilized catalase being active for decomposing hydrogen peroxide of the luminescent reagent and the catalyst;
    first means for injecting the luminescent reagent and the catalyst from the first and second vessel into the cell in said housing chamber through the column; and
    second means for measuring the quantity of light produced by the reaction between the luminescent reagent and the hydrogen peroxide of the sample in the presence of the catalyst.

[0033] According further aspect of the invention, an apparatus for detecting light produced by the reaction between a luminescent reagent and a hydrogen peroxide in a sample in the presence of a catalyst for measuring the content of the hydrogen peroxide in the sample comprises:
    a first vessel in which the luminescent reagent and an immobilized catalase active for decomposing hydrogen peroxide of the luminescent reagent are stored;
    a second vessel in which the catalyst and an immobilized catalase active for decomposing hydrogen peroxide of the catalyst are stored;
    housing means for defining an optically sealable hollow chamber, in which a cell is placed;
    first means for injecting the luminescent reagent and the catalyst from the first and second vessel into the cell in said housing chamber; and
    second means for measuring the quantity of light produced by the reaction between the luminescent reagent and the hydrogen peroxide of the sample in the presence of the catalyst.

BRIEF DESCRIPTION OF THE DRAWINGS

[0034] The present invention will be understood more fully the accompanying drawings of the preferred embodiments of the invention. The drawings are not intended to imply limitation of the invention to these specific embodiments, but are for explanation and understanding only.

[0035] In the drawings:

Figure 1 is a graph illustrating the quantity of emitted light versus the concentration of hydrogen peroxide when the reagent of the invention and the conventional reagent are used;

Figure 2 is a graph illustrating the quantity of light produced, which is an integrated value from 16 to 45 seconds after the reagent is added to the aqueous hydrogen peroxide, versus the concentration of hydrogen peroxide when the reagent of the invention and the conventional reagent are used;

Figure 3 is a graph illustrating the relationship between the quantity of emitted light and the concentration of hydrogen peroxide when reagents processed by various concentrations (0, 10, 100 and 500 U/ml) of catalase are used;

Figure 4 is a graph illustrating the relationship between the quantity of emitted light and the concentration of hydrogen peroxide when reagents processed by various concentrations (5, 10, 100, 200 and 250 U/ml) of catalase are used;

Figure 5 is a graph illustrating the quantity of emitted light, which is integrated values from 1 to 15 seconds and 16 to 30 seconds after the reagent is added to the aqeous hydrogen peroxide, versus the concentration of hydrogen peroxide when the reagent processed by 100 U/ml of catalase is used;

Figure 6 is a graph illustrating the quantity of emitted light due to a hydrogen peroxide versus time;

Figure 7 and 8 are graphs illustrating the quantity of emitted light obtained by using the reagent of the invention versus time;

Figure 9 is a graph illustrating the relationship between the quantity of emitted light and the concentration of hydrogen peroxide when a reagent of the invention is used, which reagent was caused to pass through a column in which immobilized catalase was packed;

Figure 10 is a schematic view of the preferred embodiment of an apparatus according to the invention, which has an immobilized catalase packed column;

Figure 11 is a graph illustrating the relationship between the quantity of emitted light and the concentration of hydrogen peroxide when a reagent of the invention is used, which reagent was processed by an immobilized catalase put into a nylon net bag; and

Figure 12 is a schematic view of the preferred embodiment of an apparatus according to the invention, which has a pair of tanks in which an immobilized catalase in a nylon net bag is disposed.

DETAIL DESCRIPTION OF THE PREFERRED EMBODIMENT

[0036] The present invention resides in a new reagent for use in the measurement of the content of hydrogen peroxide in a sample. The new reagent has little hydrogen peroxide, so that very small concentrations of hydrogen peroxide can be measured by using the new reagent.

[0037] According to the first preferred embodiment of the present invention, a luminescent reagent is caused to react with a catalase to decompose the hydrogen peroxide therein. Thereafter, the reaction between the catalase and the hydrogen peroxide of the reagent is stopped. In order to cause the reaction to be stopped, an inhibitor, by which the reaction is stopped, is added to the mixture of the catalase and the reagent. The inhibitor is preferably sodium azide.

[0038] A catalase, the concentration of which is 100 U/ml based on the total volume, is added to a 2 X 10⁻⁷ mol/l of luminol serving as a luminescent reagent, and the luminol is allowed to react with the catalase for one hour at a room temperature. Thereafter, a sodium azide (NaN₃), the concentration of which is 0.01 mol/l based on the total volume, is added to the reaction product, so that a reagent of the invention is formed. The reagent of the invention reacts with hydrogen peroxide in the presence of a catalyst, such as a microperoxidase, to produce light. By measuring the produced light, the content of hydrogen peroxide can be determined.

[0039] When the concentration of the catalase is adjusted to be 10 to 200 U/ml, it is not required to remove the catalase from the reagent and to cause the reaction between the catalase and the hydrogen peroxide of the reagent to be stopped.

[0040] According to the second preferred embodiment of the present invention, a luminescent reagent and/or a catalyst is caused to react with an immobilized catalase to decompose the hydrogen peroxide therein.

[0041] A water insoluble carrier is caused to react with a polyfunctional reagent, and thereafter a catalase is immobilized thereto. An aminoprophyl-CPG (controlled pore glass) and a glutaraldehyde are preferably used as the water insoluble carrier and the polyfunctional reagent, respectively. A 1 g of the aminopropyl-CPG is caused to react with 25 ml of a 2.5% of glutaraldehyde for three hours at room temperature to form aldehyde CPG. Thereafter, the aldehyde CPG is caused to react with 2 ml of a 100,000 U/ml of catalase solution for three hours at room temperature to produce an immobilized catalase. Using this immobilized catalase, the hydrogen peroxide(s) of the luminol solution and/or the catalyst solution is decomposed. That is, the luminol solution and/or the catalyst solution is caused to pass through a column, in which the immobilized catalase is packed, to form a reagent of the invention. Alternatively, the immobilized catalase may be put in a nylon net bag and added to solution(s) containing the luminol and/or the catalyst to form a reagent according to the invention.

[0042] The effectiveness of the present invention is illustrated by the following exampls.

EXAMPLE I

[0043] A catalase was added to a buffer solution containing 2 X 10⁻⁷ mol/l luminol serving as a luminescent reagent and 0.2 mol/l carbonic acid to give a 100 U/ml of catalase based on the total volume, and the luminol was caused to react with the catalase for one hour at room temperature. Thereafter, sodium azide (NaN₃) was added to the reaction product to obtain a 0.01 mol/l sodium azide based on the total volume. This solution will be referred to as " a solution A". A 0.5 ml of the solution A and 0.5 ml of an aqueous solution containing a 5 X 10⁻⁶ mol/l microperoxidase serving as a catalyst were added to 0.1ml of solutions having various concentrations (10⁻³ to 10⁻⁹ mol/l) of hydrogen peroxide to be tested. The quantity of light produced by each of the reactions between the luminol and the hydrogen peroxide in the presence of the microperoxidase was measured by a luminometer UPD-8000 (made by KABUSHIKI KAISHA MEIDENSHA) as an integrated value for 15 seconds after mixing.

[0044] As a reference, 0.5 ml of an aqueous solution containing a 2 X 10⁻⁷ mol/l luminol which was not processed by the catalase, and 0.5 ml of a 5 X 10⁻⁶ mol/l microperoxidase were added to 0.1 ml of solutions having various concentrations (10⁻³ to 10⁻⁹ mol/l) of hydrogen peroxides. The quantity of light produced by each of the respective reactions was measured in a similar manner to Example I (Reference I).

[0045] Figure 1 shows the relationship between the concentration of hydrogen peroxide and the quantity of light produced by each of the respective reactions.

[0046] In the case of Reference I, the proportion of the hydrogen peroxide included in the luminol to the aqueous hydrogen peroxide which was actually added to the luminol and the microperoxidase is relatively high when the concentration of the aqueous hydrogen peroxide is relatively low, such as less than 10⁻⁷ mol/l. As a result, the quantity of emitted light is much greater than that of light produced by the aqueous hydrogen peroxide which was actually added to the luminol and the microperoxidase. That is, the background light greatly affected the measured value when the concentration of hydrogen peroxide was less than 10⁻⁷ mol/l, so that it was difficult to measure the actual content of hydrogen peroxide in such a low concentration. On the other hand, in the case of Example I, the background light hardly affected the measured value when the concentration of hydrogen peroxide was about 10⁻⁸ mol/l. Therefore, it was found that the content of hydrogen peroxide can be accurately measured even in low concentration, up to about 10⁻⁸ mol/l, by using the reagent of the invention.

EXAMPLE II

[0047] A 0.5 ml of the solution A in Example I and 0.5 ml of an aqueous solution containing a 6 X 10⁻³ mol/l potassium ferricyanide serving as a catalyst were added to 0.1 ml of solutions having various concentrations (10⁻⁴ to 10⁻⁹ mol/l) of hydrogen peroxide. After 15 seconds, the quantity of light produced by the reaction between the luminol and the hydrogen peroxide in the presence of the potassium ferricyanide was measured for 30 seconds by a luminometer UPD-8000 to obtain an integrated value thereof.

[0048] In order to compare with Example II, 0.5 ml of a 2 X 10⁻⁷ mol/l of luminol solution which was not processed by the catalase, and 0.5 ml of a 6 X 10⁻³ mol/l of potassium ferricyanide solution were added to 0.1 ml of solutions havbing various concentrations (10⁻⁴ to 10⁻⁹ mol/l) of hydrogen peroxides. The quantity of light produced by the respective reactions was measured in a similar manner to Example II (Reference II).

[0049] Fig. 2 shows the relationship between the concentration of hydrogen peroxide and the quantity of light produced by each of the aforementioned reactions.

[0050] As shown in Fig. 2, similar results to Example I were obtained when a predetermined time passed after the solution A was added to the aqueous hydrogen peroxide. Therefore, it was found that the reagent of the invention can be used when the reagent and the sample are pipetted not only by means of an automatic pipetting device but also manually, since about ten seconds are required until a cell is set at a measuring position in a measuring apparatus after the reagent and the sample are injected into the cell.

EXAMPLE III

[0051] In order to determine the optimum concentration of catalase, the following experiment was carried out.

[0052] A catalase was added to an aqueous solution containing 2 X 10⁻⁷ mol/l luminol and 5 X 10⁻⁶ mol/1 microperoxidase to obtain slutions containing 500 U/ml, 100 U/ml and 1U/ml catalases respectively, and they were permitted to stand for one hour. Thereafter, 0.5 ml of the respective solutions were added to 0.1 ml of aqueous solutions containing 10⁻³ to 10⁻⁹ mol/l hydrogen peroxide. The quantity of light produced by the reaction between the luminol and the hydrogen peroxide in the presence of the microperoxidase in the respective samples was measured by the luminometer UPD-8000.

[0053] For reference, 0.5 ml of an aqueous solution containing 2 X 10⁻⁷ mol/l of luminol, and 0.5 ml of an aqueous solution containing 5 X 10⁻⁶ mol/l of microperoxidase were added to 0.1 ml of aqueous solutions containing 10⁻³ to 10⁻⁹ mol/l hydrogen peroxides. The quantity of light produced by the respective reactions was measured in a similar manner to Example III (Reference III).

[0054] Fig. 3 shows the relationship between the concentrations of hydrogen peroxides and the quantities of light produced by the respective reactions. When the concentration of catalase is 500 U/ml, blank value which is the quantity of emitted light when no hydrogen peroxide is contained in the sample can be decreased. However, since the amount of catalase was excessive in the solution, the hydrogen peroxide to be tested was also decomposed, so that the emitted light values of samples containing hydrogen peroxide were also decreased. On the other hand, when the concentration of catalase is 1 U/ml, the hydrogen peroxide of the luminol is not sufficiently decomposed to cause the blank value to be effectively decreased, since the concentration of catalase is too low. In this case, it was found that the optimum concentration of catalase was 100 U/ml.

EXAMPLE IV

[0055] In order to embody the optimum concentration of catalase to be added to the sample, a catalase was added to a solution containing 2 X 10⁻⁷ mol/l luminol and 5 X 10⁻⁶ mol/l microperoxidase to give solutions having 200 U/ml, 100 U/ml and 10 U/ml catalases, and they were allowed to stand for one hour. Thereafter, 0.5 ml of the respective solutions were added to 0.1 ml of aqueous solutions having various concentrations (10⁻³ to 10⁻⁹ mol/l) of hydrogen peroxide, and the quantity of light produced by the respective reactions therebetween was measured by the luminometer UPD-8000.

[0056] In order to compare with Example III, catalase was added to to a solution containing 2 X 10⁻⁷ mol/1 luminol and 5 X 10⁻⁶mol/l microperoxidase to give solutions containing 250 U/ml (Reference IV I) and 5 U/ml (Reference IV-II) catalase, which were allowed to stand for one hour. Thereafter, 0.5 ml of these solutions were respectively mixed with 0.1 ml samples containing 10⁻³ to 10⁻⁹ mol/l hydrogen peroxide, and the quantity of light produced by the respective reactions therebetween was measured in the same manner.

[0057] These results are shown in Fig. 4. As shown in Fig. 4, when the concentration of catalase are 200 U/ml, 100 U/ml and 10 U/ml, the blank value can be sufficiently decreased to improve the sensitivity of the measurement, and the hydrogen peroxide of the sample to be tested is not decomposed by excess catalase. When the concentration of catalase is greater than 200 U/ml, i.e. when it is 250 U/ml, the value of blank can be. decreased, however, since the amount of catalase in the solution is excessive, even the hydrogen peroxide to be tested is decomposed by the excess catalase, and all measured value are decreased. On the other hand, when the concentration of catalase is 5 U/ml, the hydrogen peroxide of the luminol is not sufficiently decomposed so that the blank value can not be effectively decreased, since the concentration of catalase was too low. Therefore, it was found that the optimum concentration of catalase was from 10 U/ml to 200 U/ml.

EXAMPLE V

[0058] The optimum measuring time, in which the aforementioned reagent is used in an automatic pipetting system, was determined by the following experiments.

[0059] A catalase was added to a solution containing 2 X 10⁻⁷ mol/l luminol and 5 X 10⁻⁶ mol/1 microperoxidase so that the concentration of the catalase was 100 U/ml, and was allowed to stand for one hour. Thereafter, 0.5 ml of this solution and 0.1 ml of aqueous hydrogen peroxide were injected into the cell by means of the automatic pipetting system, and the quantity of light produced by the reaction therebetween was measured by the luminometer UPD-8000 to obtain an integrated value thereof for 15 seconds after mixing.

[0060] As a reference, the quantity of emitted light produced by the aforementioned reaction was measured during a 15 second period commencing 15 seconds after mixing in the same manner, to obtain an integrated value thereof (Reference V).

[0061] The results of the above measurements are shown in Fig. 5. For reference, the result of Reference III is also represented in Fig. 5. In the case of Reference V, the blank value was decreased, but so were all of the other measured values, since the quantity of emitted light reaches its peak two or three seconds after the reagent is added to the sample in a typical luminescent phenomenon due to a hydrogen peroxide (See Fig. 6). Therefore, it was found that the quantity of emitted light was preferably measured for 15 seconds after mixing by means of an automatic pipetting device when the reagent of the invention was used.

EXAMPLE VI

[0062] In order to examine the stability of the reagent of the invention, the following experiment was carried out.

[0063] A catalase was added to a solution containing 2 X 10⁻⁷ mol/l luminol and 6 X 10⁻³ mol/l potassium ferricyanide, and the quantity of emitted light (as an integrated value for 15 seconds) was measured by the luminometer UPD-8000 immediately, half, 1, 5, 10, 15 20 and 24 hours after mixing.

[0064] These result are shown in Fig. 7. As shown in Fig. 7, it was found that the reagent of the invention was stable regardless of elapsed time.

[0065] In addition, the quantity of emitted light produced by the same mixture are also measured one week and one month after adding. As shown in Fig. 8, it was found that the reagent of the invenition was still stable after one month.

EXAMPLE VII

[0066] 

[0067] A polyfunctional reagent was caused to react with water insoluble carrier, and thereafter a catalase was attached thereto so as to immobilize the catalase. An aminopropyl-CPG (porous glass, diameter of pore; 120-200 mesh, made by ELECTRO-NUCLEONICS INC) and a glutaraldehyde were used as the water insoluble carrier and the polyfunctional reagent, respectively. A 1g of the aminopropyl-CpG was immersed in 25 ml of a buffer solution containing 2.5 % glutaraldehyde and 0.01 % phosphoric acid for three hours at room temperature to form an aldehyde CPG. Thereafter, the aldehyde CPG was caused to react with 2 ml of a buffer solution containing 100,000 U/ml catalase and 0.01 % phosphoric acid for three hours at room temperature to produce an immobilized catalase.

[0068] A luminol serving as a luminescent reagent was then caused to pass through a columun in which the aforementioned immobilized catalase was packed. A 0.5 ml of this solution and 0.5 ml of microperoxidase were added to 0.1 ml of solutions having various concentrations (10⁻³ to 10⁻⁹ mol/l) of hydrogen peroxide. The quantity of emitted light produced by the respective reactions was measured as integrated values for 15 seconds by means of the luminometer.

[0069] As a reference, luminol which was not processed by the immobilized catalase was added to 0.1 ml of each of the same hydrogen peroxides, and the quantity of emitted light was measured (Reference VII.

[0070] These results are shown in Fig. 9. In the case of Reference VII, the proportion of the hydrogen peroxide of the luminol to the hydrogen peroxide which is added with the sample to be tested is relatively high when the concentration of hydrogen peroxide in the sample is relatively low, such as less than 10⁻⁷ mol/l. As a result, the quantity of emitted light produced by the hydrogen peroxide already contained in the reaction solution is much greater than that produced by the hydrogen peroxide of the sample. That is, the background light greatly affects the measured value when the concentration of hydrogen peroxide in the sample is less than 10⁻⁷ mol/l, so that it is difficult to measure the actual content of hydrogen peroxide in such low concentrations. On the other hand, in the case of Example VII, the background light hardly affects the measured value even when the concentration of hydrogen peroxide is about 10⁻⁸ mol/l. Therefore, it was found that the content of hydrogen peroxide can be measured in concentrations of hydrogen peroxide as little as about 10⁻⁸ mol/l, by using the reagent of the invention.

[0071] According to the present invention, the method of the invention can be performed by using an apparatus shown in Fig. 10. A luminescent reagent, such as luminol, and a catalyst, such as a microperoxidase, are stored in tanks 1 and 2, respectively. The luminescent reagent and the catalyst are sucked up by means of pumps 3 and introduced into a cell 4 within a black box 5 via columns 6 in which the immobilized catalases are packed. The light produced from a sample 7 including the luminescent reagent and the catalyst is detected by a photomultiplier tube 8.

EXAMPLE VIII

[0072] The immobilized catalase which was produced in a similar manner to Example VII was put into a nylon net bag. The immobilized catalases in the nylon net bags were immersed in 100 ml of luminol solution and 100 ml of microperoxidase solution, respectively. Thereafter, 0.5 ml of the luminol solution and 0.5 ml of the microperoxidase solution were added to 0.1 ml of solutions having various concentrations (10⁻⁴ to 10⁻⁹ mol/l) of hydrogen peroxide. The quantity produced by the respective reactions was measured by luminometer UPD-8000.

[0073] As reference, by using a luminol and a microperoxidase which were not processed by the immobilized catalase, the quantity of light produced by the respective reactions was measured in the same manner.

[0074] These results are shown in Fig. 11. As shown in Fig. 11, it was found that the same results as Example VII were also obtained by this example.

[0075] According to the present invention, the method of the invention can be performed by using an apparatus shown in Fig. 12. The luminescent reagent and the catalyst are stored in tanks 11 and 12, respectively. The immobilized catalases 13 in the nylon net bags are also disposed in the respective tanks 11 and 12. The luminescent reagent and the catalyst are sucked up by means of pumps 14 and introduced into a cell 15 within a black box 16. The light produced from a sample 17 including the luminescent reagent and the catalyst is detected by a photomultiplier tube 18.

[0076] While the present invention has been disclosed in terms of the preferred embodiment in order to facilitate better understanding of the invention, it should be appreciated that the invention can be embodied in various ways without departing from the principle of the invention. Therefore, the invention should be understood to include all possible embodiments and modifications to the shown embodiments which can be embodied without departing from the principle of the invention set out in the appended claims.

Claims

1. A process for measuring the content of hydrogen peroxide in a sample comprising:
      mixing a reagent including a hydrogen peroxide with a catalase to decompose the hydrogen peroxide of the reagent;
      adding an inhibitor, by which the reaction between the catalase and the hydrogen peroxide is stopped, to the mixure of the catalase and the reagent;
      adding said reagent to said sample; and
      measuring the content of hydrogen peroxide in said sample.

2. A process as set forth in claim 1, wherein said inhibitor is a sodium azide.

3. A process for measuring the content of hydrogen peroxide in a sample comprising:
      mixing a reagent including a hydrogen peroxide which a catalase, the concentration of which is 10 to 200 U/ml based on the total volume, to decompose the hydrogen peroxide of the reagent;
      adding said reagent to said sample; and measuring the content of hydrogen peroxide in said sample.

4. A process for measuring the content of hydrogen peroxide in a sample comprising:
      bringing a reagent including a hydrogen peroxide into contact with an immobilized catalase to decompose the hydrogen peroxide in the reagent;
      adding said reagent to said sample; and
      measuring the content of hydrogen peroxide in said sample.

5. A process as set forth in claim 4, wherein said reagent is caused to pass through a column, in which said immobilized catalase is packed, to come into contact with said immobilized catalase.

6. A process as set forth in claim 4, wherein said immobilized catalase comprises a catalase which is immobilized on a carrier formed by a reaction between a water insoluble carrier and a polyfunctional reagent.

7. A reagent for use in the measurement of a hydrogen peroxide in a sample, which comprises a luminescent reagent and a catalase, the concentration of which is 10 to 200 U/ml based on the total volume.

8. A reagent as set forth in claim 7, wherein said luminescent reagent is a luminol.

9. A reagent for use in the measurement of hydrogen peroxide in a sample, which comprises a luminescent reagent and an immobilized catalase.

10. A reagent as set forth in claim 9, wherein said immobilized catalase comprises a catalase immobilized on a carrier which is formed by a reaction between a water insoluble carrier and a polyfunctional reagent.

11. A reagent as set forth in claim 10, wherein said water insolble carrier is an aminopropyl-CPG.

12. A reagent as set forth in claim 10, wherein said polyfunctional reagent is a glutaraldehyde.

13. A reagent as set forth in claim 9, wherein said luminescent reagent is a luminol.

14. A method for producing a reagent for use in the measurement of a hydrogen peroxide in a sample, which comprises the steps of:
      providing a luminescent reagent including hydrogen peroxide; and
      adding a catalase to said luminescent reagent to decompose the hydrogen peroxide therein, and thereafter removing said catalase remaining in said luminescent reagent.

15. A method for producing a reagent for use in the measurement of a hydrogen peroxide in a sample, which comprises the steps of:
      providing a luminescent reagent including hydrogen peroxide; and
      adding a catalase to said luminescent reagent to decompose the hydrogen peroxide therein, and thereafter causing the reaction between the catalase and the hydrogen peroxide in the luminescent reagent to be stopped.

16. A method as set forth in claim 15, wherein an inhibitor, by which said reaction between the catalase and the hydrogen peroxide in the luminescent reagent is stopped, is added to the mixture of the catalase and the luminescent reagent.

17. A method as set forth in claim 16, wherein said inhibitor is a sodium azide.

18. A method for producing a reagent for use in the measurement of hydrogen peroxide in a sample, which comprises the steps of:
      providing a luminescent reagent including hydrogen peroxide; and
      adding a catalase to said luminescent reagent to decompose the hydrogen peroxide therein, the amount of said catalase being previously adjusted to sufficiently decompose the hydrogen peroxide in the luminescent reagent and not to affect the hydrogen peroxide in said sample when said reagent is added to said sample.

19. A method as set forth in claim 18, wherein the concentration of said catalase is 10 to 200 U/ml based on the total volume of the luminescent reagent and the catalase.

20. A method for producing a reagent for use in the measurement of hydrogen peroxide in a sample, which comprises the steps of:
      providing a luminescent reagent including hydrogen peroxide; and
      causing said luminescent reagent to pass through a column, in which an immobilized catalase is packed, to decompose the hydrogen peroxide in the luminescent reagent.

21. A method as set forth in claim 20, wherein said immobilized catalase comprises a catalase immobilized on a carrier which is formed by a reaction between a water insoluble carrier and a polyfunctional reagent.

22. A method for producing a reagent for use in the measurement of hydrogen peroxide in a sample, which comprises the steps of:
      providing a luminescent reagent including a hydrogen peroxide; and
      adding an immobilized catalase to said luminescent reagent to decompose the hydrogen peroxide in the luminescent reagent.

23. A method as set forth in claim 22, wherein said immobilized catalase comprises a catalase immobilized on a carrier which is formed by a reaction between a water insoluble carrier and a polyfunctional reagent.

24. An apparatus for detecting light produced by the reaction between a luminescent reagent and hydrogen peroxide in a sample in the presence of a catalyst for measuring the content of the hydrogen peroxide in the sample, which comprises:
      a first vessel in which said luminescent reagent is stored;
      a second vessel in which said catalyst is stored;
      housing means for defining an optically sealable hollow chamber, in which a cell is placed;
      a column in which an immobilized catalase is packed, said immobilized catalase being active for decomposing hydrogen peroxide of said luminescent reagent and said catalyst;
      first means for injecting said luminescent reagent and said catalyst from said first and second vessel into said cell in said housing chamber through said column; and
      second means for measuring the quantity of light produced by the reaction between said luminescent reagent and said hydrogen peroxide of said sample in the presence of said catalyst.

25. An apparatus for detecting light produced by the reaction between a luminescent reagent and a hydrogen peroxide in a sample in the presence of a catalyst for measuring the content of the hydrogen peroxide in the sample, which comprises:
      a first vessel in which said luminescent reagent and an immobilized catalase active for decomposing hydrogen peroxide of said luminescent reagent are stored;
      a second vessel in which said catalyst and an immobilized catalase active for decomposing hydrogen peroxide of said catalyst are stored;
      housing means for defining an optically sealable hollow chamber, in which a cell is placed;
      first means for injecting said luminescent reagent and said catalyst from said first and second vessel into said cell in said housing chamber; and
      second means for measuring the quantity of light produced by the reaction between said luminescent reagent and said hydrogen peroxide of said sample in the presence of said catalyst.

Drawing